function BallArc(layer) {
    this.owner = new ArcObject(10);
    layer.addObject(this.owner);
}

function createWall(canvas, ctx, layer) {
    let upWall = new RectObject();
    upWall.width = ctx.canvas.width;
    upWall.height = 1;
    layer.addObject(upWall);

    let leftWall = new RectObject();
    leftWall.width = 1;
    leftWall.height = ctx.canvas.height;
    layer.addObject(leftWall);

    let downWall = new RectObject();
    downWall.width = ctx.canvas.width;
    downWall.height = 1;
    downWall.y = ctx.canvas.height;
    layer.addObject(downWall);

    let rightWall = new RectObject();
    rightWall.width = 1;
    rightWall.height = ctx.canvas.height;
    rightWall.x = ctx.canvas.width;
    layer.addObject(rightWall);

    return [upWall, rightWall, downWall, leftWall];
}
